Evaluations of effects due to low-frequency noise in a low demanding work situation

Noise sources with a dominating content of low frequencies (20–200 Hz) are found in many occupational environments. This study aimed to evaluate effects of moderate levels of low-frequency noise on attention, tiredness and motivation in a low demanding work situation. Two ventilation noises at the same A-weighted sound pressure level of 45 dB were used: one of a low-frequency character and one of a flat frequency character (reference noise). Thirty-eight female subjects worked with six performance tasks for 4 h in the noises in a between-subject design. Most of the tasks were monotonous and routine in character. Subjective reports were collected using questionnaires and cortisol levels were measured in saliva. The major finding in this study was that low-frequency noise negatively influenced performance on two tasks sensitive to reduced attention and on a proof-reading task. Performances of tasks aimed at evaluating motivation were not significantly affected. The difference in work performance was not reflected by the subjective reports. No effect of noise was found on subjective stress or cortisol levels.